DEAR DR. DONOHUE: I am a 45-year-old man. When I was 25, I had chest pain and was told by a cardiologist that I had mitral valve prolapse, MVP. For the next 10 years, I had a stress test every two years. This doctor retired, and I was switched to an associate, who ran all new tests. He told me I do not have MVP, but I have PVCs. I am confused. Are PVCs life-threatening? He put me on atenolol. I still feel my heart flip-flop but not as bad. When I get a flip-flop, I cough and get a warm sensation. Why? I started a rigorous exercise routine called kettle bell. It’s quite the heart-pounder. Is this OK? – J.L.

ANSWER: The mitral valve is the heart valve that prevents blood from backing up into the upper left heart chamber (left atrium) when the lower left heart chamber (left ventricle) pumps blood out of the heart. Mitral valve prolapse, a fairly common condition, is a ballooning of the valve into the upper left heart chamber with a heart contraction. It often produces no symptoms, and people can have it all their lives without encountering a single problem. If the mitral valve both balloons upward and leaks blood, that can be troublesome. Proof of mitral valve prolapse comes from hearing a distinctive murmur and seeing the valve balloon upward on a soundwave picture of the heart – an echocardiogram.

Premature ventricular contractions, PVCs, are extra heartbeats that originate in the lower heart chambers, the ventricles. People don’t feel the PVC. They often feel the normal beat after a PVC because the heart has filled with more blood. Many describe it as a thud in the chest. I like your “flip-flop” word.

For most, PVCs are not a health threat. They can be if they are numerous or if they are associated with any other heart conditions, such as clogged heart arteries. Your medicine, atenolol, suppresses them. Stimulants like caffeine and nicotine can increase their number. You have had many heart tests, and none has shown a serious condition. I cannot explain the cough and warm sensation they cause you.

I can’t give you the assurance you need for strenuous exercise. I believe you’re fit for anything, but your cardiologist will have to provide that information for you.

DEAR DR. DONOHUE: I am a 67-year-old woman and take two 500-mg tablets of calcium along with a multivitamin that has 250 mg of calcium. My checkups indicate I am doing fine. My sister in Germany informed me that a new study showed calcium hurts our bones and joints, and does a lot of damage. It leads to an increase in breast cancer. Does it? – S.B.

ANSWER: The daily calcium recommendation for older women is 1,200 mg to 1,500 mg. You should count the calcium you get from foods – 8 ounces of milk provides 300 mg; 8 ounces of low-fat yogurt, 415 mg; and 1 ounce of cheese, 200 mg to 300.

Calcium decreases the risk of colon cancer and some other cancers. I have never seen information that it increases breast cancer risk or causes bone or joint troubles.

DEAR DR. DONOHUE: An easy question: If a person can’t take thyroid pills because of adverse reactions, is there any other solution – like foods – to raise thyroid levels? I don’t think you’ll answer. You didn’t last time I wrote. – V.C.

ANSWER: What was the reaction? If I knew, I could address the issue better.

Synthroid is the most prescribed thyroid hormone replacement. It’s made by Abbott Laboratories. Ten other manufacturers make a similar product, and one of those might not upset you.

Desiccated thyroid is a different thyroid replacement medicine. Have you tried it? A third product is T-3. You might tolerate that one.

No food serves as a substitute for thyroid hormone.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.